"Expect a Miracle"

here is a recipe for a DIY version:

Making Crystal Gardens

Crystal Garden No. 1

* 1 brick
4 tbsp. bluing (available from: Mrs Stewart's Bluing)
4 tbsp. table salt, no iodine
1 tbsp. ammonia
4 tbsp. water food coloring
1 bowl or decorative plate

1. Break brick into chunks and place in bowl.
2. Mix salt, bluing, water, ammonia and pour over brick pieces.
3. Drop food coloring here and there on brick pieces.
4. Let sit at least overnight to several days.
Caution: crystals are very fragile.